There are many situations where it is useful to be able to detect trace amounts of amine vapors in ambient atmospheres, important ones being the hidden transport of drugs for illicit purposes, and amine air pollutants to which some workers are exposed.
Amphetamine or 2-amino-1-phenylpropane is an important drug with different pharmacological effects, including analeptic effects and is employed clinically in many areas. Unfortunately, amphetamine and its N-methyl homolog, methamphetamine, are also chemically synthesized in clandestine or illegal laboratories with the goal of supplying drugs of abuse to the illicit market.
A number of analytical methods are available for the identification and determination of amphetamine in various matrices. Recently, A. H. Lawrence and J. D. MacNeil (Anal. Chem., 54, 2385-2387, 1982) reported a method for the identification of amphetamine in street drug preparations by second derivative ultraviolet spectrometry. Numerous papers have been published describing gas chromatographic methods for the determination of amphetamine and other phenyl-alkylamine derivatives in blood, urine and other liquid biological extracts (Chromatography of Environmental Hazards, Vol. IV, L. Fishbein, Elsevier Scientific Publishing Co., N.Y. 1982, p. 311). J. K. Baker (Anal. Chem, 49, 906-908, 1977) reported the use of a gas chromatographic system equipped with dual flame ionization and nitgrogen-selective rubidium bead detectors for the identification of amphetamine, methamphetamine and other illicit drugs.
The detection of some aliphatic amines in air by adsorption onto silica gel followed by acid liquid extraction, making the extract alkaline and analyzing an aliquot of the alkaline solution by GC has been reported [National Institute for Occupational Safety and Health, Manual of Analytical Methods (Second Section) Part I, U.S. Department of Health, Education and Welfare, (NIOSH), Publ. 274-845, Cincinnati, 1977]. This latter method has a detection limit of 0.01 mg. R. H. Brown and C. J. Purnell (J. Chromatogr., 178, 79-90, 1979) investigated the capacity of a Tenax-GC [trademark] adsorber to collect vapors of a variety of organic compounds including methylamine, ethylamine, propylamine, pyridine and aniline.
In the patent literature, U.S. Pat. No. 3,711,251, L. H. Goodson et al describes, in the context of detecting alcohol or aldehyde vapors in air, an absorber-reactor containing soda lime to remove electrovalent halogen compounds downstream of a converter. U.S. Pat. No. 4,003,257, J. C. Fletcher for A. Zlatkis, describes analysis in a gas chromatographic system for trace amounts of organic volatiles in which the volatiles are trapped on a porous polymer (Tenax-GC) and, in some cases, a water condensor may be used upstream of the porous polymer. U.S. Pat. No. 4,194,884, Rounbehler et al, uses Mg or Ca silicate adsorbents for air sampling then flushes the adsorbent with solvent. U.S. Pat. No. 3,327,575, Locker, uses a magnesium salt or activated alumina to adsorb interfering materials in advance of the primary adsorber.
C. E. Andre and A. R. Mosier (Anal. Chem. 45, p. 1971-1973, 1973) reported a gas chromatographic system capable of analyzing aqueous solutions of salt of short-chain aliphatic amines. The GC inlet was modified with a short Ascarite [trademark for asbestos coated with NaOH] precolumn for releasing the free amines from their salts.
The prior art evidently has not provided a simple method of detecting trace amounts of amines, such as amphetamines, in ambient atmospheres. Using techniques similar to those in U.S. Pat. No. 4,003,257, we have tried to detect traces of amphetamines in air and were unsuccessful. The adsorbed amine was being altered in some manner.